1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to a supporting structure for a device when the device is mounted on a top surface of a body of an image forming apparatus.
2. Description of the Related Art
Image forming apparatuses such as copying machines, facsimile machines, printers, or other printing machines are configured so that electrostatic latent images formed on latent image carriers such as photoreceptors are subjected to visible image processing with a developing agent such as toner to form visible images that are then transferred and fixed onto a recording medium such as a sheet, whereby copy output can be obtained.
Sometimes an image reading device is mounted on the upper part of a body of an image forming apparatus as disclosed, for example, in Japanese Patent Laid-open Publication No. 2006-229347.
In the conventional technique disclosed in Japanese Patent Laid-open Publication No. 2006-229347 the image reading device is mounted on a casing of the image forming apparatus. Specifically, a strut portion is mounted on both side plates of the casing. Each of the strut portions is fixed to the casing by fastening or the like. Thereafter, legs of the image reading device are loaded into a fitting portion provided in the strut portions. As a result, the image reading device is supported in a cantilever beam state.
In another conventional technique disclosed in Japanese Patent Laid-open Publication No. 2007-135243 and Japanese Patent Laid-open Publication No. 2002-23440), a mounting base for mounting an image reading device is provided on opposed peripheral portions on a rectangular plane constituting a top surface of a casing of the image forming apparatus. Moreover, an adjustment member, the height of which can be adjusted, for ensuring the flatness of the mounting surface, is provided on the mounting base.
In another conventional technique disclosed in Japanese Patent Laid-open Publication No. 2001-206558, unlike the above-mentioned conventional techniques, a dedicated mounting device is provided near an image forming apparatus to mount an image reading device. In other words, the image reading device is not mounted on a casing of the image forming apparatus.
The configuration in which the image forming apparatus is mounted on the casing of the image forming apparatus is advantageous; because, unlike the configuration disclosed in Japanese Patent Laid-open Publication No. 2001-206558, no dedicated equipment is not required.
When the casing is made by resin molding, an image reading device, which is a heavy object, cannot be directly mounted on the casing. Therefore, as disclosed in Japanese Patent Laid-open Publication No. 2006-229347, strut portions or the need to be provided to bear the weight of the image reading device.
However, in order to provide the strut portions and the like, the structure of the casing of the image forming apparatus needs to be changed. Accordingly, the act of changing the structure leads to an increase in the manufacturing costs.
Further, it should be noted that the strut portions are necessary when mounting the image reading device. Therefore, a difference in details of assembling of the body casing occurs between when the image reading device is mounted and when the image reading device is not mounted, making it impossible to render components management cost and process cost uniform regardless of whether the image reading device is mounted.
In still another convention technique disclosed in Japanese Patent Laid-open Publication No. 2006-229347, the image reading device is provided above a toner feed unit in a developing device. In this configuration, when replacing a bottle in the toner feed unit, the image reading device must be first evacuated from the mounting position. Therefore, in the image reading device, which is mounted so as to be openable and closable on the top surface of the casing, since the opening/closing supporting points are the strut portions, from the viewpoint of enhancing the rigidity, the image reading device should have a large size that can withstand a considerably high level of load. Thus, the areas occupied by the supporting portion of the image reading device on the top surface of the casing are increased, leading to a possibility of an increase in size of the structure and an increase in weight of the structure. Further, in order to prevent shifting of image forming positions caused, for example, by misregistration of the image forming device supported by the body casing, it is important that the application of load from the mounted device to the body casing as an existing structure be prevented by the strut portions.